This application is based upon and claims priority of Japanese Patent Application No.2002-315188, filed on Oct. 30, 2002, the contents being incorporated herein by reference.
The present invention relates to a semiconductor device fabrication method and a semiconductor fabrication control method.
Recently, as a pretreatment for forming a gate insulation film, hydrogen annealing, i.e., a heat treatment in an atmosphere containing hydrogen is noted.
The hydrogen annealing is performed for the purposes of causing silicon on the surface of a silicon substrate to migrate to make the surface of the silicon substrate flat and removing natural oxide films formed on the surface of the silicon substrate.
The hydrogen annealing performed as a pretreatment for the step of forming a gate insulation film enables the gate insulation film to be formed in good quality, which makes it possible to fabricate semiconductor devices including transistors of good electric characteristics.
Following references disclose the background art of the present invention.
[Patent Reference 1]
Specification of Japanese Patent Application Unexamined Publication No. 2001-102321
[Patent Reference 2]
Specification of Japanese Patent Application Unexamined Publication No. 2001-274154
[Patent Reference 3]
Specification of Japanese Patent Application Unexamined Publication No. Hei 10-313012
[Patent Reference 4]
Specification of Japanese Patent Application Unexamined Publication No. 2000-340644
[Patent Reference 5]
Specification of Japanese Patent Application Unexamined Publication No. 2001-102386
[Patent Reference 6]
Specification of Japanese Patent Application Unexamined Publication No. Hei 9-326396
However, the hydrogen annealing sublimes silicon from the second side, i.e., the underside of a silicon substrate. In the chamber, a temperature sensor, etc. are disposed below the position where the silicon substrate is mounted. When the silicon sublimes from the second side of the silicon substrate, the silicon which has sublimed adheres to the temperature sensor, etc. The silicon adhering to the temperature sensor lowers the metering accuracy of the temperature sensor, which leads to the decrease of the controllability of the process. In order to ensure the controllability of the process, the semiconductor fabrication system including RTP (Rapid Thermal Process) apparatuses, etc. requires frequent maintenance, which leads to the decrease of the fabrication efficiency.
This disadvantage can take place also in controlling the semiconductor device fabrication process. That is, in controlling the semiconductor device fabrication process, for example, a gate insulation film is formed on a test semiconductor substrate, and the gate insulation film is inspected. When the inspection result is not good, the semiconductor fabrication system, etc. are maintained. In forming a gate insulation film, the same hydrogen annealing as described above is performed as a pretreatment, and in this hydrogen annealing, silicon sublimes from the second side of the silicon substrate.
Here, Patent Reference 1 described above discloses the technique of preventing the sublimation of silicon from the second side of a semiconductor wafer by feeding O2 gas to the second side of the semiconductor wafer to form an oxide film on the second side of the semiconductor wafer when the semiconductor wafer is thermally processed. In the Patent Reference 1 technique, the O2 gas flows up to the first side, i.e., the upper side of the semiconductor wafer to disadvantageously form undesired silicon oxide film on the surface of the semiconductor wafer. The silicon oxide film thus formed on the surface of the semiconductor wafer is unstable in the film thickness, which makes it very difficult to control the gate insulation film in a desired film thickness.
An object of the present invention is to provide a semiconductor device fabrication method and a semiconductor fabrication control method which, in a heat treatment, can prevent the sublimation of semiconductor constituent atoms from the second side of a semiconductor substrate without the above-described disadvantage.
According to one aspect of the present invention, there is provided a method for fabricating a semiconductor device including the step of forming a gate insulation film on a semiconductor substrate, the method further comprising, before the step of forming the gate insulation film, the steps of: forming an insulation film, covering a first side and a second side of the semiconductor substrate; etching off the insulation film on the first side of the semiconductor substrate; and annealing the semiconductor substrate with the insulation film present on the second side of the semiconductor substrate.
According to another aspect of the present invention, there is provided a method for controlling semiconductor fabrication method including the step of forming a gate insulation film on a test semiconductor substrate and the step of testing the gate insulation film, the method further comprising, before the step of forming the gate insulation film, the steps of: forming an insulation film, covering a first side and a second side of the test semiconductor substrate; etching off the insulation film on the first side of the test semiconductor substrate; and annealing the test semiconductor substrate with the insulation film present on the second side of the test semiconductor substrate.
According to further another aspect of the present invention, there is provided a method for controlling semiconductor fabrication including the step of forming a gate insulation film on a test semiconductor substrate and the step of testing the gate insulation film, the method further comprising, before the step of forming the gate insulation film, the steps of: forming an insulation film on a second side of the test semiconductor substrate; and annealing the test semiconductor substrate with the insulation film present on the second side of the test semiconductor substrate.
According to further another aspect of the present invention, there is provided a method for fabricating a semiconductor device comprising the steps of: forming a second insulation film, covering a first side and a second side of a semiconductor substrate with a first insulation film formed on the second side; forming a semiconductor film, covering the second insulation film on the first side and the second side, etching off the semiconductor film on the second side; and annealing the semiconductor substrate with the second insulation film on the second side of the semiconductor substrate.
According to further another aspect of the present invention, there is provided a method for fabricating a semiconductor device comprising the steps of: forming a first insulation film, covering a first side and a second side of the semiconductor substrate; etching off the first insulation film on the first side of the semiconductor substrate; forming a second insulation film, covering the first side and the second side of the semiconductor substrate; forming a semiconductor film, covering the second insulation film on the first side and the second side; etching off the semiconductor film on the second side; and annealing the semiconductor substrate with the second insulation film present on the second side of the semiconductor substrate.
According to the present invention, a semiconductor film on the second side (underside) of a semiconductor substrate is removed, and the semiconductor substrate is heat treated with the insulation film present on the second side of the semiconductor substrate, whereby even when the heat treatment (annealing) is performed at high temperature, the sublimation of semiconductor constituent atoms from the second side of the semiconductor substrate can be prevented. Accordingly, the adhesion of the semiconductor constituent atoms to the temperature sensor, etc. can be prevented, which permits semiconductor devices to be fabricated without complicated maintenance. Thus, according to the present invention, semiconductor devices can be fabricated with high fabrication efficiency.
According to the present invention, scrub cleaning is performed after the semiconductor film has been removed from the second side of the semiconductor substrate and before the semiconductor substrate is immersed in a cleaning liquid, whereby a considerable number of particles can be removed in the scrub cleaning. Thus, according to the present invention, a number of particles to be mixed in the cleaning liquid can be depressed when the semiconductor substrate is immersed in the cleaning liquid. According to the present invention, a number of particles adhering back to the surface of the semiconductor film, etc. can be made very small, which leads to higher fabrication yields of semiconductor devices.
According to the present invention, the heat treatment is performed with the insulation film present on the second side of the semiconductor substrate, whereby even when the high-temperature heat treatment is performed, semiconductor constituent atoms are prevented from subliming from the second side of the semiconductor substrate. According to the present invention, the adhesion of the semiconductor constituent atoms to the temperature sensor, etc. can be prevented, which permits semiconductor substrates to be fabricated without complicated maintenance. According to the present invention, semiconductor devices can be fabricated with high fabrication efficiency.
According to the present invention, the high temperature heat treatment is performed with the insulation film present on the second side of a test semiconductor substrate, whereby semiconductor constituent atoms are prevented form subliming from the second side of the test semiconductor substrate to thereby adhere to the temperature sensor, etc. Thus, according to the present invention, no complicate maintenance is required, which can improve the inspection efficiency and fabrication efficiency.